Blogs

About this blog

I'm a well-known mainframe performance guy, with almost 30 years of experience helping customers manage systems. I also dabble in lots of other technology. I've sought to widen the Performance role, incorporating aspects of infrastructural architecture.

Find us on Facebook

I don't think you can see this information but I can see what are called "Referrer URLs" for hits on this blog. (The HTTP protocol defines a header that contains the URL you came from - when you clicked on a link.) Disregarding the several "Direct" hits - which tell me nothing - I see lots of referrer URLs with some information in them, such as: Google, Yahoo etc searches. Other blogs.... [More]

Finally the last web application I use that required Internet Explorer is replaced with a Firefox-friendly version (or so we've been told). Hurrah! Except, as always, I'll believe that when I see it. (This is our Online Travel Reservations application that used an ActiveX control. Now it looks very much like an Eclipse application, except I'm certain that's just a styling thing.) And so I start to... [More]

Well, is it? Apparently there are umpteen (count'em if you want a more precise number) :-) expansions of the acronym "UCB". But the one I care most about is Unit Control Block. (I think had been born before this meaning came into being - but I'm not sure.) :-) Actually Unit Control Block was not one of the listed meanings. So I added it yesterday - but didn't write much on it. You're probably... [More]

I'm towards the end of revamping our analysis code to support (z9) and z/OS R.8. What took us so long? :-) I'm telling you this for two reasons: So you know what there is that might slow you down. So you have some view as to whether we can competently process your data. :-) System z9 About the only change in instrumentation between z990 and z9 is the separation of specialty engines into pools. But... [More]

Thanks to the people who responded to this blog entry . And to the people who talked to me offline. The result is a slight shift in emphasis: I never did talk about UIC as the primary metric of memory constraint. If you read the referenced blog item I mentioned it as one of three, alongside paging rate and free frames. The shift is that I'm going to be more strident about UIC in future, relegating... [More]

I was asked an interesting question today by a customer - one with dozens of LPARs and therefore not much time to study each one in excruciating detail... "Given that System High UIC (hereafter referred to as 'UIC') behaves differently in z/OS R.8 how should I treat it?" I've posted on this question in MXG-L Listserver, soliciting experiences and opinions. With z/OS R.8 we replaced the "page-UIC"... [More]

Last week I was at the System z Tech Conference (again getting my zeds mixed up with my zees). :-) I presented 4 times, one of which was a repeat. What's especially nice is that I got 87 attendees for the "Memory Matters in 2008" presentation - spread across 2 sessions. This was despite the second time being the very last session of the conference... and 22 people still showed up to that! So... [More]

I previously mentioned the change in zNALC LPAR setup... You can (with APAR OA20314) now specify LICENCE=ZNALC. The SCRT co-requisite is Version 14.1.0. By the way, from when you submit your SCRT report at the beginning of August you have to use this new version (until a new one is mandated) in order to be eligible for Sub-Capacity Pricing. There are a number of other changes, some of which are... [More]

I've just created a wiki to discuss primarily SMF. Mainly from the management perspective, rather than the contents of each individual record. This follows on from things I've mentioned in this blog before. If you'd like to contribute to it (and it is DESPERATELY in need of contributions right now) get a developerWorks screenname and send it to me here . Then I'll enable you to edit the wiki. You... [More]

I presented a set of (someone else's) foils on Web 2.0 to my team meeting last week. (Interestingly, being 6 months old they were already way out of date - what with Twitter and all.) Remember I'm in a mainframe crowd of effectively "gurus". :-) So why should they be interested in new-fangled webby stuff? So I got to thinking... Dear reader, why should you care about Web 2.0? The minimal answer is... [More]

It was a very good session, even if it was attended by just a "hard core" of mainframe sites. I think everyone said at least something and several said rather more than that. Here are some things I'd like to note from it... There was a general feeling that it'd be useful to have a name for a machine that could be entered on the HMC and flow through to SMF records, particularly Type 70 (CPU). So... [More]

This customer is using DB2 Hiperpools, despite being on a z9 BC processor and running DB2 Version 7. What I notice from DB2 Statistics trace is that most of the Hiperpool pages are not backed by memory. In other words they've ceased to exist. This despite there being plenty of memory in the LPAR. One thing that's also significant is that there are very few reads back from the Hiperpools. It's... [More]

... with a Performance Consultant? :-) Seriously, here's something that made me go "hmm"... I started looking at the latest set of data from a customer... Their biggest-CPU WLM workload is called "BATCH" when they told me they were a CICS shop - and that CICS was their main CPU consumer during the day. But it turns out that the biggest service class within that workload contains exclusively CICS... [More]

Regular readers would know I'm working on my "Memory Matters in 2008" presentation, which is a re-spin of the '07 Version. One of the things I talk about is IMS. Thanks to my team mate Andy Wilkinson for this list of IMS Version 10 enhancements, all of which are virtual storage usage improvements. Here are the more important items: OTMA message flood protection (prevents LSQA filling). This is... [More]